Why is battery heater overheating the motors

[R1Tom]

Sometime too much information can be harmful. Not sure why Rivian put that infomration there other than to cause anxiety in a group of people that easily get anxious.

Same reason enthusiast vehicles of all types have gauges and not just a warning light. Consumers want them.

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[HaveBlue]

It's likely the inverter that gets hot and not so much the motor.

 

[Sonartech]

For those that don’t know. Rivian (and tesla) use a coolant (which in this case I guess is also a heatant) fluid that runs between the motors and the battery. When it wants to warm the battery faster (ie to charge) then it puts resistance in the motors to heat them up. So the fluid gets warm and moves the warmth to the battery.

This is what the motors have been doing for the last 2 years on all rivians ever manufactured before we had a motor temp gauge.

so my take away, If there is no warning lights on the driver screen don’t make changes to your normal habits. The temp gauge in the infotainment screen is “infotainment”

Eh, while this may be true, it certainly isn't the rule. The motors will get super hot just running climate control before you actually drive anywhere. This morning it was 26°F in Seattle, and I warmed my car up for about 20 minutes before going to work. When I got in my car in the driveway, my motors were already 200°F+ just sitting in the driveway going nowhere. This clearly indicates that there's a resistive heater in the coolant loop providing heat - so while the motors might help with that, it ain't the only source of heat for a cold R1 sitting in the driveway.

 

[R.I.P.]

Eh, while this may be true, it certainly isn't the rule. The motors will get super hot just running climate control before you actually drive anywhere. This morning it was 26°F in Seattle, and I warmed my car up for about 20 minutes before going to work. When I got in my car in the driveway, my motors were already 200°F+ just sitting in the driveway going nowhere. This clearly indicates that there's a resistive heater in the coolant loop providing heat - so while the motors might help with that, it ain't the only source of heat for a cold R1 sitting in the driveway.

I actually don't believe this is the case. The vehicle is running current through the motors to heat them up.

This is encouraging, as this means that the vehicle is now preconditioning the motors and battery while parked.
?

 

[Zoidz]

Eh, while this may be true, it certainly isn't the rule. The motors will get super hot just running climate control before you actually drive anywhere. This morning it was 26°F in Seattle, and I warmed my car up for about 20 minutes before going to work. When I got in my car in the driveway, my motors were already 200°F+ just sitting in the driveway going nowhere. This clearly indicates that there's a resistive heater in the coolant loop providing heat - so while the motors might help with that, it ain't the only source of heat for a cold R1 sitting in the driveway.

The stator winding in the motors is used as a resistive/inductive heater. Via the "magic" of the variable frequency inverter/drive, it's possible to put significant electrical power into the motor without causing any rotation. That power turns into heat which is circulated via the coolant loop.

 

[Dark-Fx]

Eh, while this may be true, it certainly isn't the rule. The motors will get super hot just running climate control before you actually drive anywhere. This morning it was 26°F in Seattle, and I warmed my car up for about 20 minutes before going to work. When I got in my car in the driveway, my motors were already 200°F+ just sitting in the driveway going nowhere. This clearly indicates that there's a resistive heater in the coolant loop providing heat - so while the motors might help with that, it ain't the only source of heat for a cold R1 sitting in the driveway.

Only partial true. The motors are the resistive heater.

 

[Sonartech]

Seems like we should ask people that did the teardown of the R1T coolant system before too many more of you hop on the 'out-of-phase stationery motor makes all the heat' bandwagon. There's more to it than that - there's a heat exchanger in the loop. The impression I got from this video is that the motors only contribute to the coolant heat while moving, but who can say for sure what Rivian's formula for success is here. Without knowing more about a Rivian VFD for the motors, it's tough to guess what does what. Regardless, here's more info about the system:

Ya Basic (But Efficient)! Rivian R1T Thermal System - YouTube

Here's the point where they talk about the non-motor heat source:

 

[Zoidz]

Seems like we should ask people that did the teardown of the R1T coolant system before too many more of you hop on the 'out-of-phase stationery motor makes all the heat' bandwagon. There's more to it than that - there's a heat exchanger in the loop. The impression I got from this video is that the motors only contribute to the coolant heat while moving, but who can say for sure what Rivian's formula for success is here. Without knowing more about a Rivian VFD for the motors, it's tough to guess what does what. Regardless, here's more info about the system:

Ya Basic (But Efficient)! Rivian R1T Thermal System - YouTube

Here's the point where they talk about the non-motor heat source:

They said there is no PTC type heater at the beginning of the segment, and we know there is no heat pump in the coolant loop. With no heat pump, the only thing that can create heat in the refrigeration loop is air conditioning in the Rivian, which is certainly not happening in cold weather.

A heat exchanger does not create heat, it transfers heat from one thermal loop to another thermal loop, and they mention refrigeration and coolant loops, which they both stumble over a bit.

If there is no other heat source as they said, the motors have to be the heat source, and that is evidenced by the fact that the motors get hot quickly before we even start driving when the battery is cold soaked. My guess, is that like most of us, they didn't know specifically about the cold weather operating mode when she said "... [the motors] they're heating up as the vehicle begins to drive." What she said does not preclude the motors heating up before beginning to drive.

 

[Nine_One_Six_R1S]

If battery temps are sub optimal for charging or driving, the motors will run hotter as a way for the truck to efficiently warm the drive train and battery pack. If you are navigating to a charger, the same thing will happen, a message will come up stating "Preconditioning for fast charging" and your motors will start to heat up in preparation

Further, if you don't fully complete the preconditioning cycle before arriving at a charger, the truck will charge at around 27-35kW, motors will start to heat up, then after a short period once pack temps satisfy the BMS requirements, it will start charging at full rate, and motor temps will drop dramatically back to roughly 30-35c

This makes sense. But why is the OP showing only one motor warming up? Should both be warming up for Dual Motor Rivians or should all 4 be warming up for Quads.

If they are suppossed to be symetrically warming up and you see what OP sees, it's probably that one side valve may have issues.

 

[Dark-Fx]

There's more to it than that - there's a heat exchanger in the loop.

.... wouldn't it be necessary to have a heat exchanger to move heat from the motor coolant loop to the battery coolant loop?

For the record, I have not heard my AC unit cycling during preconditioning if the battery is cold like is claimed by Munro. Has anybody?

 

[R.I.P.]

.... wouldn't it be necessary to have a heat exchanger to move heat from the motor coolant loop to the battery coolant loop?

For the record, I have not heard my AC unit cycling during preconditioning if the battery is cold like is claimed by Munro. Has anybody?

Yep. He seems confused on how a heat exchanger works (like you say, it does not create heat on its own).

 

[Zoidz]

They said there is no PTC type heater at the beginning of the segment, and we know there is no heat pump in the coolant loop. With no heat pump, the only thing that can create heat in the refrigeration loop is air conditioning in the Rivian, which is certainly not happening in cold weather.

A heat exchanger does not create heat, it transfers heat from one thermal loop to another thermal loop, and they mention refrigeration and coolant loops, which they both stumble over a bit.

If there is no other heat source as they said, the motors have to be the heat source, and that is evidenced by the fact that the motors get hot quickly before we even start driving when the battery is cold soaked. My guess, is that like most of us, they didn't know specifically about the cold weather operating mode when she said "... [the motors] they're heating up as the vehicle begins to drive." What she said does not preclude the motors heating up before beginning to drive.

Replying to myself, lol.

Just to stir the pot a little on this topic, the EPA filing contradicts what the Munroe team in the video claims.

Team Munroe said there is no PTC heater, but the EPA filing says otherwise. Look at the caption for the first photo below. In the text, they state an "in-line heater element is used to heat the coolant to raise the temperature of the battery". ?

 

[dleepnw]

its a bit irresponsible to say its overheating the motors when you dont know whats happening.

 

[jeeden]

This whole thread reminds me of Gene Hackman in Crimson Tide.... "I don't trust air I can't see"

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